This invention relates to a medical observation instrument such as an otoscope which is used for observing the ear canal.
As discussed in U.S. Pat. No. 3,698,387, an otoscope comprises an elongated grip member and an observation sleeve removably attached to a distal end of the grip member. The observation sleeve is inclined longitudinally of the grip member. A physician holds this grip member by the hand, and inserts the distal end portion of the observation sleeve into the ear canal for observation. A lug is formed on an outer periphery of the observation sleeve, and a distal end portion of a holding sleeve is attached to this lug by means of an adhesive. A basal end portion of the holding sleeve is removably connected to the distal end of the grip member. A lamp is mounted in the holding sleeve. Illumination light from this lamp is supplied to the ear canal through a bundle of optical fibers.
The optical fiber bundle extends axially of the observation sleeve and is embedded in a peripheral wall of the observation sleeve, one end of the bundle is located at an end face of the lug of the observation sleeve and the other end is located at a distal end face of the observation sleeve.
In the otoscope of the above U.S. pat. publication, since various instruments are inserted into the ear canal through the observation sleeve in medical treatment, the observation sleeve is easily soiled. Accordingly, it is desirable that the soiled observation sleeve be disposable, and a new observation sleeve is used for each patient. However, since the observation sleeve thus constructed is expensive because the optical fibers are embedded therein and the lamp and the holding sleeve are attached to the lug of the observation sleeve, the observation sleeve is disposable.
With reference to other related art, an instrument for observing an anus disclosed in FIG. 3 of Japanese Utility Model Publication No. Sho 46-27034 includes an observation sleeve made of a transparent material. A projection extending in an inclined direction relative to an axis of the observation sleeve is formed on an outer periphery of the observation sleeve and is integral with the observation sleeve. This projection is also transparent. One end of the projection is removably attached to a distal end portion of a grip member. One end of an optical fiber bundle is received in the grip member, and the other end is connected to a light source. Light from the light source is supplied to one end face of the projection via the optical fiber bundle, then passed through the interior of the projection from this end face, and then passed through a peripheral wall of the observation sleeve while being reflected by inner and outer peripheral surfaces of the observation sleeve, so as to reach a distal end of the observation sleeve. Since tiny irregularities are formed on an outer periphery of the distal end of the observation sleeve, most of the light is irradiated outside from the outer periphery of the distal end of the observation sleeve. In this Publication, it is described, in order to ensure reflection, that the surfaces of the observation sleeve may be metal plated.
In the instrument disclosed in the above Utility Model Publication No. Sho 46-27034, since the projection is formed at the distal end portion of the observation sleeve, the configuration of the observation sleeve becomes complicated and the manufacturing cost of the observation sleeve becomes high. As a result, the observation sleeve becomes unsuitable to be disposed. Furthermore, since the observation sleeve is supported by the grip member with a minute end portion of the projection inserted into the grip member, the support for the observation sleeve is unstable.